The old stereotype of the latte-sipping liberal could have some basis in reality. It turns out liberals really do drink more lattes.

Researchers from the Annenberg School for Communication at the University of Pennsylvania surveyed 1,500 Americans about their coffee preferences, political ideology, household income and attitudes toward globalization and found that liberals drink more lattes.

A majority of Americans on both sides of the political spectrum preferred regular brewed coffee to lattes, but those who do drink lattes were more likely to be liberal, the study found. “Our results led to a fundamental reinterpretation of what it means to be a ‘latte liberal,’” the researchers found.

The researchers considered numerous theories for the “latte liberal” phenomenon, including the availability of lattes in a person’s neighborhood, household income and gender. While all of these were predictors of latte drinking, they did not explain the relationship between lattes and liberals.

Why do liberals appear to prefer the espresso-based beverage with an extra shot of steamed milk?

Diana Mutz, professor of political science and communication at the University of Pennsylvania, a co-author of the study, said that coffee drinkers with a more “America first” nationalistic attitude were less likely to choose lattes over regular coffee.

The latte’s name — which means milk in Italian — reflects its European roots and liberals are more open to globalization, while conservatives are more nationalistic, Mutz said. Conservatives may view lattes as foreign products or un-American ones, despite the fact that they’re made in America.

While previous studies have found that conservative and liberal voters prefer different brands, Mutz’s theory may be tough to swallow — particularly for Republican voters in traditionally red states who love to visit their local Starbucks and order whatever they fancy.

Most coffee is imported from other countries, such as Brazil, which has the record for world production, Vietnam and Colombia, according to the US Department of Agriculture. But not all coffee is imported. Coffee beans are also grown in Hawaii, California and Puerto Rico.

The origins of latte-drinking liberals are not exactly complimentary. The snarky term “latte liberals” refers to left-wing Americans who sit around and drink coffee from well-known cafes “while lamenting the plight of the poor,” according to UrbanDictionary.com.

And the differences in coffee tastes among people of various political persuasions are relatively minor. Most Americans, regardless of political ideology, still prefer coffee over lattes. Some 16 percent of liberals, 11 percent of moderates and 9 percent of conservatives prefer lattes, the latest study found.